Airplane fuselage is conventionally made by assembling fuselage portions of generally cylindrical shape, each portion including a coating or skin and strengthening elements such as stringers, frames, and specific local strengtheners for the subsequent assembly of the wings, cockpit, and landing gear for example.
To limit their weight while guaranteeing good mechanical properties, a proposal has been made for sections made out of composite materials formed of long fibers embedded in a resin matrix, particularly carbon fibers embedded in a thermosetting resin matrix. The composite material skin is conventionally obtained by draping fibers impregnated with unhardened or crude resin over the outer surface of a tool constituted by a rotating male mandrel. The fibers are applied in the form of a strip using a fiber placement head associated with a cartesian displacement system installed around the mandrel. This crude skin, with fibers impregnated with unhardened resin, is then polymerized or hardened in an autoclave oven. The strengthening elements of composite material are manufactured separately from fibers pre-impregnated with resin, then are placed in recesses of the mandrel prior to making the skin by fiber placement. The skin and the strengthening elements in their crude state are then hardened together in the autoclave. The sections thus obtained are of the closed type, with a skin that has, in transverse cross-section, a closed contour extending over 360°.
A manufacturing method of this kind, with a rotating tool, proves particularly tricky to implement. It requires implementation means that are heavy, cumbersome and complex, since the rotated mandrel has to be sufficiently rigid to stop it from bending or to limit its bending.
Furthermore, to obtain a clean outer surface condition, counter-forms, also known as formers, have to be applied against the outer surface of the crude skin for its hardening in the autoclave. These formers with their holding system are long and tedious to install, and increase the weight and volume of the assembly which has to go into the autoclave.
To avoid using formers, U.S. Pat. No. 7,048,024 proposed to make the skin of the sections by applying fibers to the inner surface of a rotating hollow mandrel. The method described only allows the manufacture of the skin of a section, without strengthening elements, and is also based on a rotating tool.